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Everything posted by Ricci

  1. FV25HP measurements are viewable now.
  2. Test data and notes for the F18 18" sealed sub and its brother the FV18 vented sub are both viewable on the main site now. Please place any discussion or comments here. Thanks,
  3. FV18 results posted...
  4. Do you have Alpine? How much is a SWS-15d2 or an SWR-1522D? $400 is a lot for a UM18.
  5. How much is an Ultimax in Belgium? How much is a 21" B&C? I'm just curious. There may be other driver options that make more sense given his location.
  6. Maximum horn compression ratio?

    Yes we are in agreement. We dove a bit deeper than expected. Again. But it happens. Yep extra mass or lowering of Fs shofts the max efficiency point down in freq. What were we supposed to be discussing? Horn compression in the throat? Ha.
  7. Maximum horn compression ratio?

    SME, Yes mass and suspension compliance affect Qts. Higher mass and stiffer suspension both squelch efficiency. No need to worry about those if strictly comparing the motor and coil systems with BL^2/Re, but in many cases what people compare is off the shelf drivers. There the Mms and compliance matter and those are factored into the final Qts value. Resultant Fs also shifts the efficiency maximum. As will the final enclosure design, etc. We really can't just look at Qts though due to complex inductance effects on these types of drivers.
  8. Maximum horn compression ratio?

    Dave, BL rating means nothing alone. That does not tell you the effective efficiency or "strength" of the motor /coil system. Resistance also has to be considered at minimum. BL^2/Re Or just look at Qts Technically the normalized inductance should also be considered as it effectively saps the efficiency and raises Qts. You need to include 3 parameters at minimum. BL, Dcr and Le. Or like I said just use the easy button and compare Qts, though that doesn't consider Le effects.
  9. Maximum horn compression ratio?

    Compared to an 18Ipal almost everything has lower motor force / efficiency. Of course the HST 18 has like twice the displacement capability though.
  10. Maximum horn compression ratio?

    I see that you also have a throat depth of just over 2". Have you seen how tall the surround is on an HST? Are you sure this enough to clearance the surround at full excursion? Im not sure how a surround like that will fare in a high pressure horn loaded app. It might be fine but I have never seen it tested. Things to consider.
  11. Maximum horn compression ratio?

    I will look at this when I get a chance. Very busy at the moment getting some more tests ready to upload. Off hand. Interesting fold. Have you considered weight of the cab and internal pressures at high output? Bracing of the panels etc? Check the particle velocities, acceleration forces and pressures at the throat and exit. They will likely be extremely high with such a high compression ratio. Also absolutely model with the Le option checked which derates motor force some.
  12. Replacement AVR / processor

    I'm still using the old Onkyo 886 myself. Probably get the Denon DN-700AV when I do change unless something better comes along. Related to the clipping with WCS signals... Most of us with big, capable systems, by default have HE / sensitivity. I've done a lot of gain investigation with my current components. My REF playback is at -7 on the master with my FL and FR channels at -15 channel trim. This is largely set by the high sensitivity of the CF-4 speakers and the extra hot input sensitivity of the Emotiva XPA-5 amp. The sub channel runs about 3dB hot at -7 trim with my K20 input sensitivities at minimum. The Onkyo will spit out over 12v through the SW jack without clipping but I do not know what point it would occur internally with a WCS. Back when I did all of that testing I did not have an easily accessed WCS signal. K20 clipping occurs well below 12 volts input. I could always increase the input gain on the amps if needed but I don't run REF +15 on the subs virtually ever. Is anybody actually running their processors at (0) for assumed REF with the channel trims near 0 or higher? You really shouldn't need to with high capability speakers but this makes me curious.
  13. B&C 21DS115

    I had a chance to pull the specs from these after a bit of mild 20Hz break in. I have the 4ohm versions. This is about as close as I've seen to matching factory specs. This driver is encouraging so far. It's light and $100 cheaper than the 21SW152. The only thing I was disappointed with so far is they used a smaller diameter spider than on the Ipal and 152. It has a smaller coil diameter so the bigger 6" formers need a bigger spider but the large one would've improved suspension linearity most likely. I assume they did it for mechanical protection where the smaller spiders increased stiffness will keep things under control if hit with too much power. More later. Specs I pulled. Like I said this is really really close. They've got a pretty low DCR on this driver but it is so efficient that the impedance peak is huge so it'll likely be at or above 3 ohms min between 10-125Hz. Parameter Value Dim Fs 31.51 Hz Re 2.2 ohms[dc] Qt 0.2 - Qes 0.2 - Qms 6.86 - Mms 379.75 grams Rms 10.95386 kg/s Cms 0.000067 m/N Vas 266.34 liters Sd 1680.02 cm^2 Bl 28.52571 Tm ETA 3.94 % Lp(2.83V/1m) 103.67 dB Le 821.03 uH L2 1930.6 uH R2 57.1 ohms L3 0 uH R3 0 ohms 1kHz Le 2.62mH
  14. Measurements and test notes are live...Discuss here. It's a bad Mamma Jamma. Enjoy.
  15. JTR Speakers Captivator 212Pro Discussion

    Perhaps you are right. The point about mechanical damage happening due to a stress or strain overload of the cone is likely true. You would almost expect a catastrophic failure or fracture somewhere. I still don't think this is related to "normal" over excursion. Those things can surely happen, but I would expect them to happen in the low bass register as well. Assuming a sealed cabinet, in order to produce xmax at 80Hz we would expect output roughly 12dB higher than at 40hz. There can be some differences of course due to real world signal reproduction and other variances but this is close. So if a driver produces 110dB at 40Hz at 15mm excursion we would expect it to produce roughly 4dB higher output each 1/3rd octave up when driven to the same 15mm excursion. 114dB at 50Hz, 118dB at 63Hz and 122dB at 80Hz etc. Velocity and acceleration forces increase accordingly as well. reaching the same excursion an octave up requires 2x the cone velocity and 4x the acceleration. In some cases there is some form of distress or other "bad" noise that occurs well prior to this 4dB per 1/3rd octave expected increase. You mention that a dramatic drop off in motor force or "control" of the moving assembly is lost at the excursion extremes which is true. This could result in an overshoot effect where excursion would increase as the moving assembly is not "grabbed" and returned. Sort of like a loss of traction on the voice coil. However for the SPL to not increase with the greater cone displacement it basically has to behave in a manner that is not following the waveform of the drive signal. It would be a sort of clipping almost. Sort of like the speaker jumping out of the track provided by the electrical waveform. Indeed when I experience this it often is accompanied by a captured waveform that is completely different than expected and utter garbage. If the output waveform is not the 80Hz or whatever expected and is instead some terrible distorted mess with squared off components it would reduce the measured SPL. Perhaps it doesn't appear at lower frequencies is because the velocity and acceleration forces are lower and the suspension can better deal with controlling the assembly. Hmmm. I'd never quite thought of it like that. That may just be a possibility. I do seem to see it more often with lighter weight moving assemblies and softer suspensions though. We are way off topic and none of this pertains to the Cap212-Pro exactly, but this is a fairly common occurrence using the K20 for burst testing.
  16. Any discussion of this speaker or the measurements should go here. Enjoy.
  17. Just made all of the good stuff for this visible. Please discuss here.
  18. Ricci's Skhorn Subwoofer & Files

    I don't think anyone has but you could. I wouldn't advise it for actual touring use but if they won't be moved that much it should be ok.
  19. KRK Systems 12S2

    All discussion of this 12" commercial unit and its measurements should go here. Thanks.
  20. I thought it would be fun for everyone to list their equipment and maybe post a few pics here so others can see what each of us is rocking out on. Here is my 2 main systems that get used. I am not going to bother listing everything else... Ricci HT / Room is roughly 9x14x26 carpeted on cement slab with 3 brick walls, a fireplace, an opening to a hallway and french doors. Untreated as of yet... Electronics Samsung 75" LED UN75J6300 PS4 Onkyo PR-SC886P (Intermittent HDMI issue again / 3rd time on the search for something.) Emotiva XPA-5 / Main speakers Powersoft K20-DSP+AESOP's (x2) (240v line) / Subs Speakers Klipsch CF-4's (L/R) Klipsch KV-4 (CC) Klipsch CF-4's (SL/SR) (8x) RF T3S1-19's in 4 dual opposed sealed cabs of about 4.5cu ft per driver. Wired to 2ohms each cab and 2 cabs wired in series to a K20-Dsp amplifier. Amplifiers running bridged into 4ohms nominal per 4 drivers. Ricci's Band Space PA Behringer QX2442USB Presonus Firestudio 2626 Presonus Digimax F/S Behringer DCX2496 (x2) Mackie m1400i (HF) Behringer Inuke 6000 (Mid) Crest 8002 x2 (LF) Speakers JBL 2360B horn lenses with 2446H CD's JBL 4675C cabs loaded with AE TD15M-4ohm Apollo drivers wired in series Pair of M.A.U.L. subwoofers
  21. JTR Speakers Captivator 212Pro Discussion

    Those are different things. Breakup modes due to bending forces in the cone geometry and composition are basically resonances. These occur even at very low volumes and are a separate issue IMHO. Basically they are inherent to the driver. This is something that does not occur until the speaker is driven extremely hard. Usually harder than any user scenario would ever push it. If things are continually pushed harder and harder the forces on the speaker increase and eventually something will break or start to behave very badly. Have you ever looked at the forces involved to produce some of the burst output numbers recorded? Acceleration or velocity for example? The forces involved are way beyond the scope of normal use. Lighter more flexible materials will tend to give more. What happens to the mass at the edge of the cone when the voice coil acceleration at the center of the cone is constantly increased? I doubt it is IMD or flux modulation effects I just don't see them making the sorts of noises I've heard. In some examples a driver will go from producing a relatively clean pure sounding tone to a clearly mechanical almost bottoming out sound in the 63-125Hz bands with only a small increase in the input signal. However it is not actually bottoming out or hitting suspension limits and the amplifier is well below clipping. That is easily verified. The signal captured goes from a normal looking reproduction to a complete unnatural mess.
  22. JTR Speakers Captivator 212Pro Discussion

    I have a theory that some of the lighter cones start to flex due to extremely high forces placed on them during the burst testing. It is something I have noticed on those types of drivers over the years. At the 80 to 125Hz bands the driver may not be able to reach xmax or even the THD limitations for the testing before something starts to sound wrong. This will usually be noted as mechanical noise on the burst chart. I stop at that point because it is a clear indicator not to proceed further as damage may occur. It is just a theory and could be any number of things though. In this case it really doesn't matter that the cab wouldnt take more than 110v. It means a less powerful and costly amp can be used and get all of the available performance.
  23. Acoustics Studies

    He has some good articles on his site if some of you are unfamiliar with it.
  24. B&C 21DS115

    I woukd definitely use it when modeling any subwoofer. You have to remember that the final result will likely be a bit smoother due to losses and unaccounted for variations in the real speaker. I like to look at sims with and without both and make sure both look ok, but the LE model will be closer.
  25. B&C 21DS115

    The 21SW115 is definitely not a match. The 21DS115-4 should be ok. David, the response should be somewhere in between the LE modeled and without LE modeled in HR.